Nearly an hour earlier, a second student was robbed of his phone and assaulted in an alley adjacent to Shaw’s supermarket, near Packard’s Corner, the statement said.

He was punched after being approached by two men at about 11:30 p.m.

One man was described as being between 5 feet 6 inches and 5 feet 8 inches tall, and wearing a dark jacket.

The student refused medical treatment.

The third robbery happened around 1:25 a.m., when a man and woman approached a student sitting on the stairs of 275 Babcock St., a dormitory in the heart of the BU campus.

The man allegedly pushed the student to the ground, opened her purse, and took a cellphone and some money, according to the statement.

The pair fled in a older model white sedan.

“This is a very concerning series of events, and such an unusual circumstance,” said Colin Riley, Boston University spokesman.

In a statement, university police advised students to follow “basic safety precautions,” including avoiding poorly lit areas late at night, getting a ride instead of walking, and staying aware of surroundings by not using headphones or talking on the phone.

Brookline, Boston, and university police are investigating. According to the statement, university and Brookline police will add patrols to the area of the robberies.

Anyone with information is asked to call university police at 617-353-2121.

In September and October, a string of four robberies in Brookline, near the BU campus, worried the university community and prompted calls for student vigilance.

In December, a Norfolk County grand jury indicted three Boston teens in the robberies.

Globe correspondent Zachary T. Sampson contributed to this report. Chris Stuck-Girard can be reached at chrisstuckgirard@gmail.com.